U.S. patent application number 16/797833 was filed with the patent office on 2021-08-26 for model reference adaptive control algorithm to address the vehicle actuation dynamics.
The applicant listed for this patent is Baidu USA LLC. Invention is credited to Jiangtao HU, Shu JIANG, Qi LUO, Jinghao MIAO, Jingao WANG, Yu WANG, Jiaxuan XU, Jinyun ZHOU.
Application Number | 20210261160 16/797833 |
Document ID | / |
Family ID | 1000004682767 |
Filed Date | 2021-08-26 |
United States Patent
Application |
20210261160 |
Kind Code |
A1 |
WANG; Yu ; et al. |
August 26, 2021 |
MODEL REFERENCE ADAPTIVE CONTROL ALGORITHM TO ADDRESS THE VEHICLE
ACTUATION DYNAMICS
Abstract
Systems and methods are disclosed for reducing second order
dynamics delays in a control subsystem (e.g. throttle, braking, or
steering) in an autonomous driving vehicle (ADV). A control input
is received from an ADV perception and planning system. The control
input is translated in a control command to a control subsystem of
the ADV. A reference actuation output is obtained from a storage of
the ADV. The reference actuation output is a smoothed output that
accounts for second order actuation dynamic delays attributable to
the control subsystem actuator. Based on a difference between the
control input and the reference actuation output, adaptive gains
are determined and applied to the input control signal to reduce
error between the control output and the reference actuation
output.
Inventors: |
WANG; Yu; (Sunnyvale,
CA) ; LUO; Qi; (Sunnyvale, CA) ; JIANG;
Shu; (Sunnyvale, CA) ; MIAO; Jinghao;
(Sunnyvale, CA) ; HU; Jiangtao; (Sunnyvale,
CA) ; WANG; Jingao; (Sunnyvale, CA) ; ZHOU;
Jinyun; (Sunnyvale, CA) ; XU; Jiaxuan;
(Sunnyvale, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baidu USA LLC |
Sunnyvale |
CA |
US |
|
|
Family ID: |
1000004682767 |
Appl. No.: |
16/797833 |
Filed: |
February 21, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60W 60/0015 20200201;
B60W 10/10 20130101; B60W 10/20 20130101; B60W 10/18 20130101 |
International
Class: |
B60W 60/00 20060101
B60W060/00; B60W 10/10 20060101 B60W010/10; B60W 10/18 20060101
B60W010/18; B60W 10/20 20060101 B60W010/20 |
Claims
1. A computer-implemented method of actuating a control subsystem
of an autonomous driving vehicle (ADV) control system, the method
comprising: receiving a first control input to a feedback
controller of an actuation control system of the control subsystem
of an ADV; determining an error between an output actuation command
of an actuator of the control subsystem and a reference actuation
output generated by a model reference system that is based upon a
second control input; determining an adaptive gain that is based
upon the error; and outputting a second actuation command to
actuate the control subsystem based upon a measured actuation
action output by the control subsystem, the first control input,
and the adaptive gain.
2. The method of claim 1, wherein reference actuation output is
based at least in part on second order attributes of the control
subsystem.
3. The method of claim 2, wherein the second order attributes of
the control subsystem include one or more of: time-latency in
initiating a control action of the control subsystem, a rise time,
an overshoot amount, or a settling time of an actuator of the
control subsystem.
4. The method of claim 1, wherein the first control input is
received at the feedback controller during a current driving cycle
of the ADV and the second control input was received at the
feedback controller during a prior driving cycle.
5. The method of claim 1, wherein the first control input and the
second control input are received from an autonomous driving system
that is configured to plan a trajectory to drive the ADV based on
sensor data obtained from a plurality of sensors of the ADV in view
of vehicle states obtained from a vehicle chassis of the ADV.
6. The method of claim 1, wherein the control subsystem comprises
at least one of a throttle control subsystem, a braking control
subsystem, or a steering control subsystem.
7. The method of claim 1, further comprising iteratively performing
determining an error between an output actuation command of the
actuator of the control subsystem and the reference actuation
output, determining an adaptive gain, and outputting a next
actuation command to actuate the control subsystem, until a
measured state of actuation of the control subsystem is within a
threshold value of the reference actuation output with an applied
adaptive gain.
8. A non-transitory machine-readable medium having instructions
stored therein, which when executed by a processor, cause the
processor to perform operations of actuating a control subsystem of
an autonomous driving vehicle (ADV) control system, the operations
comprising: receiving a first control input to a feedback
controller of an actuation control system of the control subsystem
of an ADV; determining an error between an output actuation command
of an actuator of the control subsystem and a reference actuation
output generated by a model reference system that is based upon a
second control input; determining an adaptive gain that is based
upon the error; and outputting a second actuation command to
actuate the control subsystem based upon a measured actuation
action output by the control subsystem, the first control input,
and the adaptive gain.
9. The machine-readable medium of claim 8, wherein reference
actuation output is based at least in part on second order
attributes of the control subsystem.
10. The machine-readable medium of claim 9, wherein the second
order attributes of the control subsystem include one or more of:
time-latency in initiating a control action of the control
subsystem, a rise time, an overshoot amount, or a settling time of
an actuator of the control subsystem.
11. The machine-readable medium of claim 8, wherein the first
control input is received at the feedback controller during a
current driving cycle of the ADV and the second control input was
received at the feedback controller during a prior driving
cycle.
12. The machine-readable medium of claim 8, wherein the first
control input and the second control input are received from an
autonomous driving system that is configured to plan a trajectory
to drive the ADV based on sensor data obtained from a plurality of
sensors of the ADV in view of vehicle states obtained from a
vehicle chassis of the ADV.
13. The machine-readable medium of claim 8, wherein the control
subsystem comprises at least one of a throttle control subsystem, a
braking control subsystem, or a steering control subsystem.
14. The machine-readable medium of claim 8, wherein the operations
further comprise iteratively performing determining an error
between an output actuation command of the actuator of the control
subsystem and the reference actuation output, determining an
adaptive gain, and outputting a next actuation command to actuate
the control subsystem, until a measured state of actuation of the
control subsystem is within a threshold value of the reference
actuation output with an applied adaptive gain.
15. An actuation control system for actuating a control subsystem
of an autonomous driving vehicle (ADV) control system of an ADV,
the actuation control system comprising: a feedback controller to
receive a first control input; a model reference module coupled to
the feedback controller; a by-wire actuation system coupled to the
feedback controller; a combine logic to determine an error between
an output actuation command of the by-wire actuation system and a
reference actuation output generated by the model reference system
that is based upon a second control input; and an adaptive gain
system to determine an adaptive gain that is based upon the error,
wherein the feedback controller is configured to output a second
actuation command to actuate the by-wire actuation system based
upon a measured actuation action output by the by-wire actuation
system, the first control input, and the adaptive gain.
16. The system of claim 15, wherein reference actuation output is
based at least in part on second order attributes of the by-wire
actuation system.
17. The system of claim 16, wherein the second order attributes of
the by-wire actuation system include one or more of: time-latency
in initiating a control action of the by-wire actuation system, a
rise time, an overshoot amount, or a settling time of an actuator
of the by-wire actuation system.
18. The system of claim 15, wherein the first control input is
received at the feedback controller during a current driving cycle
of the ADV and the second control input was received at the
feedback controller during a prior driving cycle.
19. The system of claim 15, wherein the first control input and the
second control input are received from an autonomous driving system
that is configured to plan a trajectory to drive the ADV based on
sensor data obtained from a plurality of sensors of the ADV in view
of vehicle states obtained from a vehicle chassis of the ADV.
20. The system of claim 15, wherein the by-wire actuation system
comprises at least one of a throttle control subsystem, a braking
control subsystem, or a steering control subsystem.
Description
TECHNICAL FIELD
[0001] Embodiments of the present disclosure relate generally to
operating autonomous vehicles. More particularly, embodiments of
the disclosure relate to an efficient, real-time process for
addressing time-latency and actuation dynamic delay in control
autonomous vehicle control subsystems, to improve autonomous
vehicle control.
BACKGROUND
[0002] Vehicles operating in an autonomous mode (e.g., driverless)
can relieve occupants, especially the driver, from some
driving-related responsibilities. When operating in an autonomous
mode, the vehicle can navigate to various locations using onboard
sensors, allowing the vehicle to travel with minimal human
interaction or in some cases without any passengers.
[0003] Motion planning and control are critical operations in
autonomous driving. However, conventional motion planning
operations estimate the difficulty of completing a given path
mainly from its curvature and speed (first order dynamics), without
considering the second order dynamics of control subsystems, such
as brakes, throttle, and steering.
[0004] Due to the usage of electronic determination and actuation
of control systems such as brakes, throttle, and steering
("drive-by-wire"), there exists some latency time and system
dynamic delays in the vehicle actuation system. Time-latency can
occur due to delay in detecting that a control command is needed to
stay on the planned trajectory. Time-latency can be attributable to
data collection and processing time needed to identify objects
surrounding the vehicle and attributable to computing of a control
command needed to stay on the planned trajectory. Time-latency can
be on the order of 50-100 milliseconds (ms). Actuation dynamic
delay can occur in a control subsystem when a control command is
received by a control subsystem, such as brakes, throttle, or
steering, and the control subsystem must actuate physical
components to execute the control command. Actuation dynamic delay
can result in undesired throttling/braking/steering control
responses, especially during rapid acceleration or sharp turning
driving scenarios. For example, in a typical side-pass driving
scenario, when the autonomous vehicle quickly changes to another
lane from a current lane, the steering action usually presents some
dynamic lag compared with the desired steering angle that is based
on the steering command from the control module. As a result, the
overall lane changing process can become unsmooth and be
uncomfortable for passengers in the vehicle.
[0005] Actuation dynamic delay can be attributable to physical
actuators or elements, such as motors, drive belts, brake pads and
cylinders, or combustion, needing time to implement the physical
actions that implement the control command. Actuation dynamic delay
of a received command can manifest as a rise time of the actuation,
an overshoot amount, and a settling time for a measured state of
the physical actuator to match the received control command.
Actuation dynamic delay can be on the order of several hundreds of
milliseconds, substantially longer than latency.
[0006] Control subsystems such as brakes, steering, and throttle,
are often provided by third-party suppliers, different from the
party that develops a control system for the autonomous vehicle.
Thus, developers of autonomous vehicle control subsystems must
consider the operational characteristics of the control subsystems
as a "black box." Accordingly, previous industrial efforts in the
autonomous vehicle field attempt to design a simple
proportional-integral-derivative (PID) controller on steering
actuation to reduce the negative effects of the actuation dynamics.
However, due to the over-simplified structure of PID-based
controller, the PID controller can only increase the steering
dynamic response to some extent, but cannot fully address the
actuation time-latency and dynamic delay problem.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Embodiments of the disclosure are illustrated by way of
example and not limitation in the figures of the accompanying
drawings in which like references indicate similar elements.
[0008] FIG. 1 is a block diagram illustrating a networked system
according to one embodiment.
[0009] FIG. 2 is a block diagram illustrating an example of an
autonomous vehicle according to one embodiment.
[0010] FIGS. 3A and 3B are block diagrams illustrating an example
of a perception and planning system used with an autonomous vehicle
according to one embodiment.
[0011] FIG. 3C illustrates an example ADV control command and an
autonomous vehicle control subsystem actuation action response to
the control command, according to an embodiment.
[0012] FIG. 3D illustrates a steering control subsystem as used in
an autonomous vehicle, and sources of dynamics, according to an
embodiment.
[0013] FIG. 4 is a block diagram illustrating architecture of an
autonomous driving system according to one embodiment.
[0014] FIG. 5A is a block diagram 500 illustrating a data flow and
a system that incorporates a model reference adaptive controller
(MRAC) that improves actuation of one or more control subsystems of
an autonomous driving vehicle (ADV), according to one
embodiment.
[0015] FIG. 5B is a block diagram illustrating a data flow of the
model reference adaptive controller, according to one
embodiment.
[0016] FIG. 5C is a block diagram illustrating subsystem control
actuation, as modified by the model reference adaptive controller,
according to one embodiment.
[0017] FIG. 6 is a block diagram illustrating a method of improving
actuation of a control subsystem (e.g. throttle, braking, steering)
using a model reference adaptive controller, according to one
embodiment.
[0018] FIG. 7 is a block diagram illustrating a method of improving
actuation of a control subsystem (e.g. throttle, braking, steering)
using a model reference adaptive controller, according to one
embodiment.
DETAILED DESCRIPTION
[0019] Various embodiments and aspects of the disclosures will be
described with reference to details discussed below, and the
accompanying drawings will illustrate the various embodiments. The
following description and drawings are illustrative of the
disclosure and are not to be construed as limiting the disclosure.
Numerous specific details are described to provide a thorough
understanding of various embodiments of the present disclosure.
However, in certain instances, well-known or conventional details
are not described in order to provide a concise discussion of
embodiments of the present disclosures.
[0020] Reference in the specification to "one embodiment" or "an
embodiment" means that a particular feature, structure, or
characteristic described in conjunction with the embodiment can be
included in at least one embodiment of the disclosure. The
appearances of the phrase "in one embodiment" in various places in
the specification do not necessarily all refer to the same
embodiment.
[0021] In an embodiment, a method of improving performance of a
control subsystem of an autonomous driving vehicle (ADV) control
system includes receiving a control input to a feedback controller
of an actuation system of the control subsystem (e.g. throttle,
braking, steering) of the ADV. A reference actuation output
corresponding to the control input is determined. The model
reference actuation output can be determined by looking up the
reference actuation output corresponding to the control subsystem
and received control input, in a storage of the ADV. The reference
actuation output can be based at least in part on actuation time
latency and second order dynamics delays of the control subsystem.
The second order dynamics delays of the control subsystem can
include one or more of: time-latency in initiating a control action
of the control subsystem, a rise time of the actuation, an
overshoot amount of the actuation, or a settling time of the
actuation of the control subsystem. The method also includes
determining an error between an output actuation command of an
actuator of the control subsystem and the reference actuation
output, and determining an adaptive gain that is based upon the
error. An actuation command is outputted to actuate the control
subsystem. The actuation command is based upon the measured
actuation action, desired input and the adaptive gain.
[0022] In an embodiment, the method includes repeating the
operations of determining an error between an output actuation
command of the actuator of the control subsystem and the reference
actuation output, and determining an adaptive gain that is based
upon the error; and outputting a next actuation command to actuate
the control subsystem, until a measured state of actuation of the
control subsystem is within a threshold value of the reference
actuation output. The actuation command can be based upon the
measured actuation action, desired input and the adaptive gain.
[0023] In an embodiment, any/all of the above method functionality
can be implemented by a processing system, comprising one or more
hardware processors coupled to a memory programmed with executable
instructions that, when executed by the processing system, cause a
computing system to implement the claimed functionality. In an
embodiment, the memory can be a non-transitory computer-readable
medium or other type of memory.
[0024] FIG. 1 is a block diagram illustrating an autonomous vehicle
network configuration according to one embodiment of the
disclosure. Referring to FIG. 1, network configuration 100 includes
autonomous vehicle 101 that may be communicatively coupled to one
or more servers 103-104 over a network 102. Although there is one
autonomous vehicle shown, multiple autonomous vehicles can be
coupled to each other and/or coupled to servers 103-104 over
network 102. Network 102 may be any type of networks such as a
local area network (LAN), a wide area network (WAN) such as the
Internet, a cellular network, a satellite network, or a combination
thereof, wired or wireless. Server(s) 103-104 may be any kind of
servers or a cluster of servers, such as Web or cloud servers,
application servers, backend servers, or a combination thereof.
Servers 103-104 may be data analytics servers, content servers,
traffic information servers, map and point of interest (MPOI)
servers, simulated autonomous vehicle driving servers, or location
servers, etc. An autonomous vehicle driving simulator server 104
can include data logging of driving records substantially identical
to the data logging of a real autonomous driving vehicle. The
driving simulator can be used to test proposed updates to
autonomous vehicle control systems. The driving simulator can
upload its driving records for processing by, e.g., server 103
algorithms 124 to generate a set of standardized metrics 124 that
characterize performance of the autonomous vehicle control
system.
[0025] An autonomous vehicle 101 refers to a vehicle that can be
configured to be driven in an autonomous mode in which the vehicle
navigates through an environment with little or no input from a
driver. Such an autonomous vehicle can include a sensor system
having one or more sensors that are configured to detect
information about the environment in which the vehicle operates.
The vehicle and its associated controller(s) use the detected
information to navigate through the environment. Autonomous vehicle
101 can operate in a manual mode, a full autonomous mode, or a
partial autonomous mode. As described herein, in some embodiments,
an autonomous vehicle is simulated in an autonomous driving
simulator of server 104. Characteristics and identifiers, such as
an autonomous vehicle type (e.g. Lexus.RTM., Honda.RTM.,
SmartCar.RTM., Kia.RTM., et al.) and an autonomous vehicle
controller type (e.g. model predictive control, or linear quadratic
regulator) can be used to identify simulated autonomous vehicles
within an autonomous driving simulation system and driving records
generated by a simulated autonomous vehicle driving session.
[0026] In one embodiment, autonomous vehicle 101 includes, but is
not limited to, perception and planning system 110, vehicle control
system 111, wireless communication system 112, user interface
system 113, and sensor system 115. Autonomous vehicle 101 may
further include certain common components included in ordinary
vehicles, such as, an engine, wheels, steering wheel, transmission,
etc., which may be controlled by vehicle control system 111 and/or
perception and planning system 110 using a variety of communication
signals and/or commands, such as, for example, acceleration signals
or commands, deceleration signals or commands, steering signals or
commands, braking signals or commands, etc.
[0027] Components 110-115 may be communicatively coupled to each
other via an interconnect, a bus, a network, or a combination
thereof. For example, components 110-115 may be communicatively
coupled to each other via a controller area network (CAN) bus. A
CAN bus is a vehicle bus standard designed to allow
microcontrollers and devices to communicate with each other in
applications without a host computer. It is a message-based
protocol, designed originally for multiplex electrical wiring
within automobiles, but is also used in many other contexts.
[0028] Referring now to FIG. 2, in one embodiment, sensor system
115 includes, but it is not limited to, one or more cameras 211,
global positioning system (GPS) unit 212, inertial measurement unit
(IMU) 213, radar unit 214, and a light detection and range (LIDAR)
unit 215. GPS system 212 may include a transceiver operable to
provide information regarding the position of the autonomous
vehicle. IMU unit 213 may sense position and orientation changes of
the autonomous vehicle based on inertial acceleration. Radar unit
214 may represent a system that utilizes radio signals to sense
objects within the local environment of the autonomous vehicle. In
some embodiments, in addition to sensing objects, radar unit 214
may additionally sense the speed and/or heading of the objects.
LIDAR unit 215 may sense objects in the environment in which the
autonomous vehicle is located using lasers. LIDAR unit 215 could
include one or more laser sources, a laser scanner, and one or more
detectors, among other system components. Cameras 211 may include
one or more devices to capture images of the environment
surrounding the autonomous vehicle. Cameras 211 may be still
cameras and/or video cameras. A camera may be mechanically movable,
for example, by mounting the camera on a rotating and/or tilting a
platform.
[0029] Sensor system 115 may further include other sensors, such
as, a sonar sensor, an infrared sensor, a steering sensor, a
throttle sensor, a braking sensor, and an audio sensor (e.g.,
microphone). An audio sensor may be configured to capture sound
from the environment surrounding the autonomous vehicle. A steering
sensor may be configured to sense the steering angle of a steering
wheel, wheels of the vehicle, or a combination thereof. A throttle
sensor and a braking sensor sense the throttle position and braking
position of the vehicle, respectively. In some situations, a
throttle sensor and a braking sensor may be integrated as an
integrated throttle/braking sensor.
[0030] In one embodiment, vehicle control system 111 includes, but
is not limited to, steering unit 201, throttle unit 202 (also
referred to as an acceleration unit), and braking unit 203.
Steering unit 201 is to adjust the direction or heading of the
vehicle. Throttle unit 202 is to control the speed of the motor or
engine that in turn controls the speed and acceleration of the
vehicle. Braking unit 203 is to decelerate the vehicle by providing
friction to slow the wheels or tires of the vehicle.
[0031] Control system 111 may further comprise subsystem
controllers 206. Subsystem controllers 205 can include a controller
for the steering unit 201, a controller for the throttle unit 202,
and a controller for the braking unit 203. Each subsystem
controller 205 receives one or more control commands from the ADV
control system 111. As described with reference to FIG. 3C, below,
the ADV control system 111 receives a trajectory path for the ADV
to follow to navigate a portion of an ADV route. The control system
111 can determine an amount of steering, braking, and/or throttling
that is needed to navigate the ADV along the trajectory path.
Control system 111 then issues one or more commands to one or more
control subsystems (steering unit 201, throttle unit 202, braking
unit 203). A steering command can be in the form of a target
steering angle, e.g. to the left or right of straight ahead,
expressed in degrees or radians. A throttle command from the
control system 111 to the throttle unit 202 can be e.g. a target
speed, acceleration, or percentage of full throttle. A braking
command from the control system 111 to the braking unit 203 can be,
e.g. a target speed, a deceleration rate, or a percentage of full
braking. Each control command from control system 111 to a control
subsystem (steering unit 102, throttle 202, or braking 203) can be
translated into a physical action on the control subsystem by a
controller within the subsystem.
[0032] The physical actuation by a control subsystem of a command
received from the control system 111 is not immediate. A
time-latency in physical actuation represents a difference between
a time issuing of a command from the controller 111 and the time
that the subsystem controller outputs a command to begin the physic
actuation. After execution of the command begins by the subsystem
controller, dynamic delays exist in executing the command to attain
the physical target actuation commanded by the controller 111. The
systems and methods described herein determine metrics for each
subsystem controller that characterizes the time-latency and
dynamic delays in physical actuation of the subsystem. An example
command from an ADV controller to a subsystem controller, and the
resulting time-latency and actuation dynamics of the subsystem are
described below with reference to FIG. 3C.
[0033] Subsystem controller(s) 205 can include storage for
reference actuation outputs 206, storage 207 for e.g. parameters of
the dynamic models, storage 208 for adaptive gains, and logic or
updates for one or more model reference adaptive controllers (MRAC)
209. Reference actuation outputs 206, adaptive gains 208, and MRACs
209 are described more fully, below, with reference to FIGS.
5A-5C.
[0034] Subsystem controllers 205 can be integrated with ADV
controller 111 or as third-party stand-alone subsystem controllers.
In practice, subsystem controllers are often third-party
controllers such that the ADV control system communicates with the
subsystem controller via a programming interface, and the specifics
of how a command is executed and actuated by the control subsystem
are a "black box" to the ADV controller designer. Compensating for
the time-latency and actuation dynamic delays of a subsystem, as
described herein, enable an ADV to adaptively account for
time-latency and actuation dynamic delays of a subsystem without
needing to know the cause or reason for the time-latency and
actuation dynamic delays. Control subsystem time-latency and
actuation dynamic delay are particularly important in driving
scenarios that require rapid braking, accelerating, or steering.
Note that the components as shown in FIG. 2 may be implemented in
hardware, software, or a combination thereof.
[0035] Referring back to FIG. 1, wireless communication system 112
is to allow communication between autonomous vehicle 101 and
external systems, such as devices, sensors, other vehicles, etc.
For example, wireless communication system 112 can wirelessly
communicate with one or more devices directly or via a
communication network, such as servers 103-104 over network 102.
Wireless communication system 112 can use any cellular
communication network or a wireless local area network (WLAN),
e.g., using WiFi to communicate with another component or system.
Wireless communication system 112 could communicate directly with a
device (e.g., a mobile device of a passenger, a display device, a
speaker within vehicle 101), for example, using an infrared link,
Bluetooth, etc. User interface system 113 may be part of peripheral
devices implemented within vehicle 101 including, for example, a
keyboard, a touch screen display device, a microphone, and a
speaker, etc.
[0036] Some or all of the functions of autonomous vehicle 101 may
be controlled or managed by perception and planning system 110,
especially when operating in an autonomous driving mode. Perception
and planning system 110 includes the necessary hardware (e.g.,
processor(s), memory, storage) and software (e.g., operating
system, planning and routing programs) to receive information from
sensor system 115, control system 111, wireless communication
system 112, and/or user interface system 113, process the received
information, plan a route or path from a starting point to a
destination point, and then drive vehicle 101 based on the planning
and control information. Alternatively, perception and planning
system 110 may be integrated with vehicle control system 111.
[0037] For example, a user as a passenger may specify a starting
location and a destination of a trip, for example, via a user
interface. Perception and planning system 110 obtains the trip
related data. For example, perception and planning system 110 may
obtain location and route information from an MPOI server, which
may be a part of servers 103-104. The location server provides
location services and the MPOI server provides map services and the
POIs of certain locations. Alternatively, such location and MPOI
information may be cached locally in a persistent storage device of
perception and planning system 110.
[0038] While autonomous vehicle 101 is moving along the route,
perception and planning system 110 may also obtain real-time
traffic information from a traffic information system or server
(TIS). Note that servers 103-104 may be operated by a third party
entity. Alternatively, the functionalities of servers 103-104 may
be integrated with perception and planning system 110. Based on the
real-time traffic information, MPOI information, and location
information, as well as real-time local environment data detected
or sensed by sensor system 115 (e.g., obstacles, objects, nearby
vehicles), perception and planning system 110 can plan an optimal
route and drive vehicle 101, for example, via control system 111,
according to the planned route to reach the specified destination
safely and efficiently.
[0039] Autonomous driving vehicle (ADV) 101 can generate and log
driving records that capture data from the subsystems, e.g. sensor
system 115, control system 111, and perception and planning system
110. The driving records can be uploaded to a server, e.g. server
103, for storage by data collector 121. A cross-platform control
profiling system, stored in e.g. server 103 algorithms and models
124, can analyze driving records from a large plurality of ADVs and
simulated ADVs to generate driving
[0040] Server 103 may be a data analytics system to perform data
analytics services for a variety of clients. In one embodiment,
data analytics system 103 includes data collector 121 and machine
learning engine 122. Data collector 121 collects driving statistics
123 from a variety of vehicles, either autonomous vehicles or
regular vehicles driven by human drivers. Driving statistics 123
include information indicating the driving commands (e.g.,
throttle, brake, steering commands) issued and responses of the
vehicles (e.g., speeds, accelerations, decelerations, directions)
captured by sensors of the vehicles at different points in time.
Driving statistics 123 may further include information describing
the driving environments at different points in time, such as, for
example, routes (including starting and destination locations),
MPOIs, road conditions, weather conditions, etc.
[0041] Based on driving statistics 123, machine learning engine 122
generates or trains a set of rules, algorithms, and/or predictive
models 124 for a variety of purposes. In one embodiment, algorithms
124 may include a cross-platform control profiling system that
generates a set of standardized statistics, or metrics, 123
characterizing performance of an autonomous driving control system
of the ADV using ADV driving data and simulated ADV driving data
("cross-platform" meaning both real and simulated ADV driving
records). Raw driving data records are uploaded from an ADV at a
specified time, or manually, to date collector 121. Simulated ADV
driving data is also uploaded to data collector 121. Algorithms 124
are used to generate the set of set of standardized metrics
characterizing the performance of the ADV control system. The
metrics are stored in driving statistics 123, and distributed to
subscribing users, such as design engineers.
[0042] FIGS. 3A and 3B are block diagrams illustrating an example
of a perception and planning system used with an autonomous vehicle
according to one embodiment. System 300 may be implemented as a
part of autonomous vehicle 101 of FIG. 1 including, but is not
limited to, perception and planning system 110, control system 111,
and sensor system 115. Referring to FIGS. 3A-3B, perception and
planning system 110 includes, but is not limited to, localization
module 301, perception module 302, prediction module 303, decision
module 304, planning module 305, control module 306, routing module
307, and driving logger 308.
[0043] Some or all of modules 301-308 may be implemented in
software, hardware, or a combination thereof. For example, these
modules may be installed in persistent storage device 352, loaded
into memory 351, and executed by one or more processors (not
shown). Note that some or all of these modules may be
communicatively coupled to or integrated with some or all modules
of vehicle control system 111 of FIG. 2. Some of modules 301-308
may be integrated together as an integrated module.
[0044] Localization module 301 determines a current location of
autonomous vehicle 300 (e.g., leveraging GPS unit 212) and manages
any data related to a trip or route of a user. Localization module
301 (also referred to as a map and route module) manages any data
related to a trip or route of a user. A user may log in and specify
a starting location and a destination of a trip, for example, via a
user interface. Localization module 301 communicates with other
components of autonomous vehicle 300, such as map and route
information 311, to obtain the trip related data. For example,
localization module 301 may obtain location and route information
from a location server and a map and POI (MPOI) server. A location
server provides location services and an MPOI server provides map
services and the POIs of certain locations, which may be cached as
part of map and route information 311. While autonomous vehicle 300
is moving along the route, localization module 301 may also obtain
real-time traffic information from a traffic information system or
server.
[0045] Based on the sensor data provided by sensor system 115 and
localization information obtained by localization module 301, a
perception of the surrounding environment is determined by
perception module 302. The perception information may represent
what an ordinary driver would perceive surrounding a vehicle in
which the driver is driving. The perception can include the lane
configuration, traffic light signals, a relative position of
another vehicle, a pedestrian, a building, crosswalk, or other
traffic related signs (e.g., stop signs, yield signs), etc., for
example, in a form of an object. The lane configuration includes
information describing a lane or lanes, such as, for example, a
shape of the lane (e.g., straight or curvature), a width of the
lane, how many lanes in a road, one-way or two-way lane, merging or
splitting lanes, exiting lane, etc.
[0046] Perception module 302 may include a computer vision system
or functionalities of a computer vision system to process and
analyze images captured by one or more cameras in order to identify
objects and/or features in the environment of autonomous vehicle.
The objects can include traffic signals, road way boundaries, other
vehicles, pedestrians, and/or obstacles, etc. The computer vision
system may use an object recognition algorithm, video tracking, and
other computer vision techniques. In some embodiments, the computer
vision system can map an environment, track objects, and estimate
the speed of objects, etc. Perception module 302 can also detect
objects based on other sensors data provided by other sensors such
as a radar and/or LIDAR.
[0047] For each of the objects, prediction module 303 predicts what
the object will behave under the circumstances. The prediction is
performed based on the perception data perceiving the driving
environment at the point in time in view of a set of map/rout
information 311 and traffic rules 312. For example, if the object
is a vehicle at an opposing direction and the current driving
environment includes an intersection, prediction module 303 will
predict whether the vehicle will likely move straight forward or
make a turn. If the perception data indicates that the intersection
has no traffic light, prediction module 303 may predict that the
vehicle may have to fully stop prior to enter the intersection. If
the perception data indicates that the vehicle is currently at a
left-turn only lane or a right-turn only lane, prediction module
303 may predict that the vehicle will more likely make a left turn
or right turn respectively.
[0048] For each of the objects, decision module 304 makes a
decision regarding how to handle the object. For example, for a
particular object (e.g., another vehicle in a crossing route) as
well as its metadata describing the object (e.g., a speed,
direction, turning angle), decision module 304 decides how to
encounter the object (e.g., overtake, yield, stop, pass). Decision
module 304 may make such decisions according to a set of rules such
as traffic rules or driving rules 312, which may be stored in
persistent storage device 352.
[0049] Routing module 307 is configured to provide one or more
routes or paths from a starting point to a destination point. For a
given trip from a start location to a destination location, for
example, received from a user, routing module 307 obtains route and
map information 311 and determines all possible routes or paths
from the starting location to reach the destination location.
Routing module 307 may generate a reference line in a form of a
topographic map for each of the routes it determines from the
starting location to reach the destination location. A reference
line refers to an ideal route or path without any interference from
others such as other vehicles, obstacles, or traffic condition.
That is, if there is no other vehicle, pedestrians, or obstacles on
the road, an ADV should exactly or closely follows the reference
line. The topographic maps are then provided to decision module 304
and/or planning module 305. Decision module 304 and/or planning
module 305 examine all of the possible routes to select and modify
one of the most optimal routes in view of other data provided by
other modules such as traffic conditions from localization module
301, driving environment perceived by perception module 302, and
traffic condition predicted by prediction module 303. The actual
path or route for controlling the ADV may be close to or different
from the reference line provided by routing module 307 dependent
upon the specific driving environment at the point in time.
[0050] Based on a decision for each of the objects perceived,
planning module 305 plans a path or route for the autonomous
vehicle, as well as driving parameters (e.g., distance, speed,
and/or turning angle), using a reference line provided by routing
module 307 as a basis. That is, for a given object, decision module
304 decides what to do with the object, while planning module 305
determines how to do it. For example, for a given object, decision
module 304 may decide to pass the object, while planning module 305
may determine whether to pass on the left side or right side of the
object. Planning and control data is generated by planning module
305 including information describing how vehicle 300 would move in
a next moving cycle (e.g., next route/path segment). For example,
the planning and control data may instruct vehicle 300 to move 10
meters at a speed of 30 mile per hour (mph), then change to a right
lane at the speed of 25 mph.
[0051] Based on the planning and control data, control module 306
controls and drives the autonomous vehicle, by sending proper
commands or signals to vehicle control system 111, according to a
route or path defined by the planning and control data. The
planning and control data include sufficient information to drive
the vehicle from a first point to a second point of a route or path
using appropriate vehicle settings or driving parameters (e.g.,
throttle, braking, steering commands) at different points in time
along the path or route.
[0052] In one embodiment, the planning phase is performed in a
number of planning cycles, also referred to as driving cycles, such
as, for example, in every time interval of 100 milliseconds (ms).
For each of the planning cycles or driving cycles, one or more
control commands will be issued based on the planning and control
data. That is, for every 100 ms, planning module 305 plans a next
route segment or path segment, for example, including a target
position and the time required for the ADV to reach the target
position. Alternatively, planning module 305 may further specify
the specific speed, direction, and/or steering angle, etc. In one
embodiment, planning module 305 plans a route segment or path
segment for the next predetermined period of time such as 5
seconds. For each planning cycle, planning module 305 plans a
target position for the current cycle (e.g., next 5 seconds) based
on a target position planned in a previous cycle. Control module
306 then generates one or more control commands (e.g., throttle,
brake, steering control commands) based on the planning and control
data of the current cycle.
[0053] Note that decision module 304 and planning module 305 may be
integrated as an integrated module. Decision module 304/planning
module 305 may include a navigation system or functionalities of a
navigation system to determine a driving path for the autonomous
vehicle. For example, the navigation system may determine a series
of speeds and directional headings to affect movement of the
autonomous vehicle along a path that substantially avoids perceived
obstacles while generally advancing the autonomous vehicle along a
roadway-based path leading to an ultimate destination. The
destination may be set according to user inputs via user interface
system 113. The navigation system may update the driving path
dynamically while the autonomous vehicle is in operation. The
navigation system can incorporate data from a GPS system and one or
more maps so as to determine the driving path for the autonomous
vehicle.
[0054] Driving logger 308 records driving records from at least
three data channels of the ADV control system: the control channel,
the chassis channel, and the localization channel. The control
channel produces information about control commands to control
systems of the ADV, such as braking, throttle, and steering. The
chassis channel produces information from various sensors, such as
accelerometers, and readings of actual positions or actuations of
the braking, throttle, and steering systems. The localization
channel produces information regarding the actual location and
heading of the ADV with reference to a standard reference such as a
high-definition (HD) map or a global positioning satellite (GPS)
system. Data records can be recorded at approximately 100 frames
per second (fps), or at about 10 milliseconds (ms) per frame. Each
driving record has a timestamp. A timestamp can be an absolute
timestamp in the form of hh:mm:ss:ms (hours, minutes, seconds,
milliseconds) relative to a start time, such as the start of a
driving route. In embodiment, the timestamp can be a frame number,
relative to a start time such as the start of the driving route. In
an embodiment, each driving record can additional have a date stamp
in addition to the time stamp. Data logger 308 can log driving
records for simulated ADV driving sessions as well as real-world
ADV driving sessions.
[0055] Data logger 308 can write the driving records to a
non-volatile storage such as driving logs storage 313. Driving logs
313 can be uploaded to a server system, e.g. server(s) 103-104, to
generate a set of standardized performance metrics that grade the
performance of a controller of the ADV. The controller of the ADV
can be updated using the standardized set of metrics, and the
updated controller of the ADV can be stored in non-volatile storage
314.
[0056] As shown on FIG. 3B, data logger 308 can also receive
driving records from the planning module. The planning module
driving records can be used to compare planned driving conditions
vs. actual (or simulated) driving conditions, to grade the
performance of the ADV controller.
[0057] FIG. 3C illustrates an example ADV control command and an
autonomous vehicle control subsystem actuation action response to
the control command, according to an embodiment. A hypothetical
example control command 350 is shown as a step function. In
practice, control inputs typically are not step functions. However,
the control input well-illustrates the concepts to be described
herein. Control command 350 has a time-latency 355. The
time-latency is a time between a control input given by ADV control
system 111, given to an ADV control subsystem (e.g. throttle,
steering, brakes), and the beginning of actuation of the control
subsystem in response to the control input.
[0058] The control command 350 can be passed through a low-pass
filter 351 before being passed to the subsystem actuation 352.
ADV's are "drive-by-wire," meaning that the control subsystem
actuation is via transmission of a control command. In practice,
control subsystem actuators are often provided by third parties,
different from the designers of the ADV or the ADV controller.
Thus, while the designer of the ADV or ADV controller is aware that
there are actuation delays, such as rise time 356, overshoot 357,
and rise time 356, the designer of the ADV or ADV controller does
not know the exact sources or causes of the actuation delays. To
the ADV designer or ADV controller designer, the control subsystem
actuator is merely a "black box," which has actuation delays in
relation to input control commands. Systems and methods described
herein can account for the actuation delays and time-latency using
a reference actuation output, adaptive gains, and a closed loop
subsystem controller.
[0059] FIG. 3D illustrates a steering control subsystem as used in
an autonomous vehicle, and sources of dynamics, according to an
embodiment.
[0060] Steering control subsystem 360 is an example control
subsystem of ADV 101. Steering subsystems in ADVs are typically
"drive by wire" systems that receive a control command, e.g.
control command 350, and execute the control command through
physical and electronic means. Steering control subsystem 360 can
include a belt drive 361, a hand wheel feedback motor 363, a hand
wheel angle sensor 362, a steering actuator 364, a pinion angle
sensor, and tires. Steering actuator 364, e.g., and tires, may
introduce sources of actuation dynamic delay.
[0061] FIG. 4 is a block diagram illustrating system architecture
for autonomous driving according to one embodiment. System
architecture 400 may represent system architecture of an autonomous
driving system as shown in FIGS. 3A and 3B. Referring to FIG. 4,
system architecture 400 includes, but it is not limited to,
application layer 401, planning and control (PNC) layer 402,
perception layer 403, driver layer 404, firmware layer 405, and
hardware layer 406. Application layer 401 may include user
interface or configuration application that interacts with users or
passengers of an autonomous driving vehicle, such as, for example,
functionalities associated with user interface system 113. PNC
layer 402 may include functionalities of at least planning module
305 and control module 306. Perception layer 403 may include
functionalities of at least perception module 302. In one
embodiment, there is an additional layer including the
functionalities of prediction module 303 and/or decision module
304. Alternatively, such functionalities may be included in PNC
layer 402 and/or perception layer 403. System architecture 400
further includes driver layer 404, firmware layer 405, and hardware
layer 406. Firmware layer 405 may represent at least the
functionality of sensor system 115, which may be implemented in a
form of a field programmable gate array (FPGA). Hardware layer 406
may represent the hardware of the autonomous driving vehicle such
as control system 111. Layers 401-403 can communicate with firmware
layer 405 and hardware layer 406 via device driver layer 404.
[0062] FIG. 5A is a block diagrams illustrating a data flow and a
system 500 that incorporates a model reference adaptive controller
(MRAC) that improves actuation of one or more control subsystems of
an autonomous driving vehicle (ADV), according to one embodiment.
Control subsystems can include braking, throttling, and steering
systems of the ADV. When actuating a control subsystem using
"drive-by-wire", there are second order dynamics delays and a
time-latency of the control subsystem. Second order dynamics delays
can include rise time, overshoot, and settling time of the measured
state of actuation of the control subsystem, relative to the input
actuation command. Actuation control system 550 can reduce the
second order actuation dynamic delays to produce a smoother
actuation control of a control subsystem using model reference 560,
model reference adaptive control (MRAC) feedback controller 555,
and MRAC adaptive gain system 570.
[0063] The system 500 includes a vehicle control system 505 and an
actuation control system 550. Actuation control system 550 can
include functionality for all control subsystems (throttle,
braking, steering). In an embodiment, one or more control
subsystems each have a respective actuation control system 550.
Vehicle control system 505 can include a vehicle system controller
515 and calibration table 520. Vehicle control system 505 can be
considered an "outer loop" with respect to actuation control system
550 being an "inner loop" which can iterate as fast, or faster,
than the vehicle control system 505 "outer loop."
[0064] In operation, vehicle control system 505 receives a planning
trajectory, r, 510, from a perception and planning system, e.g.
perception and planning system 111, of the ADV. A summing circuit
511 receives the planning and trajectory 510 signal and also
receives a state output, x, 576 of the vehicle system 575. State
output 576 represents a current measured state of actuation of a
control subsystem of vehicle system (e.g. chassis) 575. For
example, planning and trajectory 510 may specify that a steering
subsystem is commanded to be actuated to 8.degree. left of center,
and state output 576 reports that the current state of the steering
subsystem is 5.degree. left of center. Summing circuit 511 can
report the difference as an additional 3.degree. left of center, to
vehicle system controller 515.
[0065] Vehicle system controller 515 can be any type of ADV vehicle
controller such as model predictive controller (MPC) or a linear
quadratic regulator (LQR). Vehicle system controller 515 outputs a
control command 516 (e.g. a steering command) to calibration table
520. Calibration table 520 generates a subsystem control actuation
command 521, e.g. a command to actuate the steering control
subsystem to the planning trajectory 510 input of 8.degree. with a
steering input of an additional 3.degree. left of center command
(desired input 522) to achieve the 8.degree. left of center
indicated in the planning and trajectory signal 510. The desired
input, r, 522 is input to both the MRAC feedback controller 555 and
the model reference (desired actuation) 560.
[0066] Referring now to FIG. 5B, an example desired input 522 is
shown as a step function input to the actuation control system 550.
In practice, input to an actuation system of a control subsystem is
rarely a step function. However, the step function serves to
illustrate the second order actuation dynamics of actuation control
system 550. Second order actuation dynamics are also described
above, with reference to FIG. 3C.
[0067] The function of model reference 560 is to create a "desired"
system to compare with the "imperfect" actuation system of vehicle
control system 505, then the error between the model reference 560
and the vehicle control system 505 is used in the adaptive process
to adaptively generate gains so that the control subsystem
actuation can achieve the model reference, within a threshold
tolerance. Model reference 560 can look up a reference actuation
output 561 that corresponds to the received desired input 522. The
reference actuation output can be retrieved from reference
actuation outputs 206 of subsystem controller(s) 205 as shown with
reference to FIG. 2, above. Model reference 560 can be a machine
generated, or a manually generated, actuation curve that takes into
account the second order dynamics delays of the control subsystem.
For example, given the example desired input 522, model reference
560 looks up example desired reference output, x.sub.REF 561.
Desired reference output 561 is received by summation circuit
567.
[0068] At substantially the same time that model reference 560 is
determining reference actuation output 561, MRAC feedback
controller 555 receives desired input 522. Assuming that time
desired input 561 was received by MRAC feedback controller 555 is
received at a time t.sub.0, MRAC feedback controller 555 will not
yet have received adaptive gains related to desired input 522.
Thus, at time t.sub.0, MRAC feedback controller may pass desired
input 522 to by-wire actuation system 565 as actuation command, u,
566, without adaptive gains 571. In practice, by-wire actuation
system 565 is very often a third party component which is treated
as a black box. Thus, by-wire actuation system 565 generates an
actuation action, x 566 in accordance with the programming or logic
of actuation system 565 as produced by the manufacturer of by-wire
actuation system 565. Actuation action 566 is received by (1)
summation circuit 567 and (2) by MRAC feedback controller 555 as
input for MRAC feedback controller 555 at time t.sub.1.
[0069] Summation circuit 567 determines a control error, e, 569
that is the difference between the actuation action 566 output by
the by-wire actuation system 565 at time t.sub.0 and the reference
actuation output 561 by model reference 560 at time t.sub.0. MRAC
adaptive gain system 570 determines an amount of adaptive gain 571
to pass to MRAC feedback controller 555 to determine an actuation
command 566 to transmit to by-wire action 565 at time t.sub.1. MRAC
adaptive gain system 570 performs on-line adjustments using
adaptive gains to ensure the convergence and stability of the
closed-loop actuation control system 550. In an embodiment,
adaptive gain 571 can be determined by MRAC adaptive gain system
570 as follows.
[0070] (1) "Ideal" feedback control, with "ideal" gains:
u = k x * .times. x + k r * .times. r , wherein ##EQU00001## k x *
= a ref - a b , k r * = b ref b , and ##EQU00001.2## x . = ax + bu
x . = a ref .times. x + b ref .times. r ##EQU00001.3##
[0071] (2) Adaptive feedback control with estimated, time-varying
gains:
u={circumflex over (k)}.sub.x(t)x+{circumflex over (k)}.sub.r(t)r,
where
{dot over ({circumflex over
(k)})}.sub.x=-.gamma..sub.xx(x-x.sub.ref),
{dot over ({circumflex over
(k)})}.sub.r=-.gamma..sub.rr(x-x.sub.ref), and
[0072] .gamma..sub.x, .gamma..sub.r, >0 are constant adaptive
gains that determine the convergence rate of the adaptive
process.
[0073] (3) Actual system--reference system:
(x-{dot over (x)}.sub.ref)=a(x-x.sub.ref)+b({circumflex over
(k)}.sub.x(t)x-k.sub.x*x.sub.ref)+b({circumflex over
(k)}.sub.r(t)r+k.sub.r*r)
[0074] (4) Closed-loop error dynamics is given by the nonlinear,
non-autonomous 3.sup.rd order system:
e = x - x ref .times. output .times. .times. error .times. e . = a
ref .times. e + b .times. k _ x .function. [ e + x ref ] + b
.times. k _ r .times. r , .times. k _ x .function. ( t ) = k ^ x
.function. ( t ) - k x * .times. adaptive .times. .times. gain
.times. .times. error .times. k _ . x = - .gamma. x .times. e
.function. [ e + x ref ] , and ##EQU00002## k _ r .function. ( t )
= k ^ r .function. ( t ) - k r * .times. adaptive .times. .times.
gain .times. .times. error .times. k _ . r = - .gamma. r .times. r
. ##EQU00002.2##
[0075] (5) The non-linear, time-varying stability system expression
is:
=a.sub.refe+bk.sub.x[e+x.sub.ref(t)]+bk.sub.rr(t),
{dot over (k)}.sub.x=-.gamma..sub.xe[e+x.sub.ref(t)], and
{dot over (k)}.sub.r=-.gamma..sub.rr(t).
As e.fwdarw.0,x(t).fwdarw.x.sub.ref(t).
[0076] MRAC feedback controller 555 generates a realizable
actuation control command 556 by feeding back the inputs and states
of the control subsystem using the dynamically-tuned adaptive gains
571. The control command 556 is sent to the by-wire actuation
system 565, to further produce an actuation action 566 in the next
iteration, which is closer to the reference actuation action
561.
[0077] Referring now to FIG. 5C, further illustrating the details
of FIGS. 5A and 5B, example reference actuation output 561 is
summed with example actuation action 566 by summing or combining
circuit 567. The combined result is output as control error 569 to
the MRAC feedback gain system 570. The result of applying the
adaptive gains from MRAC adaptive gain system 570 to the actuation
action 566 generates an actuation signal 571 with reduced error for
a next iteration of the MRAC adaptive gain system 570 and MRAC
feedback controller 555.
[0078] FIG. 6 is a block diagram illustrating a method 600 of
improving actuation of a control subsystem (e.g. throttle, braking,
steering) using a model reference adaptive controller (MRAC),
according to one embodiment.
[0079] In operation 601, a control input is received to a feedback
controller 555 of an actuation control system 550 of a control
subsystem (e.g. throttle, brake, or steering) of an ADV.
[0080] In operation 602, a reference actuation output corresponding
to the received control input can be determined. In an embodiment,
the reference actuation output for the control subsystem
corresponding to the received control input can be looked up in a
storage of subsystem controllers 205, in reference actuation
outputs 206.
[0081] In operation 603, an error amount between an output
actuation command of an actuator of the control subsystem, and the
reference actuation output, can be determined. The error amount can
be determined, e.g., by summing circuit 567 of actuation control
system 550 as described above with reference to FIG. 5A-5C.
[0082] In operation 604, an adaptive gain amount can be determined,
using the error amount.
[0083] In operation 605, the second actuation command to actuate
the control subsystem that is based upon the measured actuation
action, desired input and the adaptive gain, is output to the
control subsystem. Method 600 ends.
[0084] FIG. 7 is a block diagram illustrating a method 700 of
improving actuation of a control subsystem (e.g. throttle, braking,
steering) using a model reference adaptive controller, according to
one embodiment.
[0085] In operation 701, a control input is received to a feedback
controller 555 of an actuation control system 550 of a control
subsystem (e.g. throttle, brake, or steering) of an ADV.
[0086] In operation 702, an reference actuation output
corresponding to the received control input can be determined. In
an embodiment, the reference actuation output for the control
subsystem corresponding to the received control input can be looked
up in a storage of subsystem controllers 205, in reference
actuation outputs 206. The reference actuation output can be based
at least in part on second order dynamic delays of the control
system.
[0087] In operation 703, an error amount between an output
actuation command of an actuator of the control subsystem, and the
reference actuation output, can be determined. The error amount can
be determined, e.g., by summing circuit 567 of actuation control
system 550, as described above with reference to FIG. 5A-5C.
[0088] In operation 704, an adaptive gain amount can be determined,
using the error amount. In an embodiment, the adaptive gain can be
based at least in part upon time-varying adaptive gains, and
constant adaptive gains that determine a convergence rate of the
adaptive process. The adaptive gain can be applied to the reference
actuation output to obtain a second actuation command to the
control subsystem.
[0089] In operation 705, a second actuation command can be output
to actuate the control subsystem. The second actuation command is
based upon the measured actuation output, desired input and the
adaptive gain.
[0090] In operation 706, operations 703-705 can be repeated until a
measured state of the actuated control subsystem is within a
threshold value of the reference actuation output with applied
adaptive gain. Method 700 ends.
[0091] Note that some or all of the components as shown and
described above may be implemented in software, hardware, or a
combination thereof. For example, such components can be
implemented as software installed and stored in a persistent
storage device, which can be loaded and executed in a memory by a
processor (not shown) to carry out the processes or operations
described throughout this application. Alternatively, such
components can be implemented as executable code programmed or
embedded into dedicated hardware such as an integrated circuit
(e.g., an application specific IC or ASIC), a digital signal
processor (DSP), or a field programmable gate array (FPGA), which
can be accessed via a corresponding driver and/or operating system
from an application. Furthermore, such components can be
implemented as specific hardware logic in a processor or processor
core as part of an instruction set accessible by a software
component via one or more specific instructions.
[0092] Some portions of the preceding detailed descriptions have
been presented in terms of algorithms and symbolic representations
of operations on data bits within a computer memory. These
algorithmic descriptions and representations are the ways used by
those skilled in the data processing arts to most effectively
convey the substance of their work to others skilled in the art. An
algorithm is here, and generally, conceived to be a self-consistent
sequence of operations leading to a desired result. The operations
are those requiring physical manipulations of physical
quantities.
[0093] It should be borne in mind, however, that all of these and
similar terms are to be associated with the appropriate physical
quantities and are merely convenient labels applied to these
quantities. Unless specifically stated otherwise as apparent from
the above discussion, it is appreciated that throughout the
description, discussions utilizing terms such as those set forth in
the claims below, refer to the action and processes of a computer
system, or similar electronic computing device, that manipulates
and transforms data represented as physical (electronic) quantities
within the computer system's registers and memories into other data
similarly represented as physical quantities within the computer
system memories or registers or other such information storage,
transmission or display devices.
[0094] Embodiments of the disclosure also relate to an apparatus
for performing the operations herein. Such a computer program is
stored in a non-transitory computer readable medium. A
machine-readable medium includes any mechanism for storing
information in a form readable by a machine (e.g., a computer). For
example, a machine-readable (e.g., computer-readable) medium
includes a machine (e.g., a computer) readable storage medium
(e.g., read only memory ("ROM"), random access memory ("RAM"),
magnetic disk storage media, optical storage media, flash memory
devices).
[0095] The processes or methods depicted in the preceding figures
may be performed by processing logic that comprises hardware (e.g.
circuitry, dedicated logic, etc.), software (e.g., embodied on a
non-transitory computer readable medium), or a combination of both.
Although the processes or methods are described above in terms of
some sequential operations, it should be appreciated that some of
the operations described may be performed in a different order.
Moreover, some operations may be performed in parallel rather than
sequentially.
[0096] Embodiments of the present disclosure are not described with
reference to any particular programming language. It will be
appreciated that a variety of programming languages may be used to
implement the teachings of embodiments of the disclosure as
described herein.
[0097] In the foregoing specification, embodiments of the
disclosure have been described with reference to specific exemplary
embodiments thereof. It will be evident that various modifications
may be made thereto without departing from the broader spirit and
scope of the disclosure as set forth in the following claims. The
specification and drawings are, accordingly, to be regarded in an
illustrative sense rather than a restrictive sense.
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